Energy attenuation apparatus for a system conveying liquid under pressure and method of attenuating energy in such a system

ABSTRACT

An energy attenuation apparatus for a system conveying liquid under pressure, and a method for attenuating energy in such a system, are provided. The apparatus includes a hose or tubular casing having an inlet opening for receiving liquid from the system, and an outlet opening for returning the liquid to the system. An inlet conduit extends concentrically into the hose or tubular casing, with an annular space being formed between the inlet conduit and the tubular casing. At least one aperture for introducing liquid into the annular space from the inlet conduit is provided on a portion thereof that is disposed in the tubular casing.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation-in-Part application of applicants' applicationSer. No. 09/030,031, filing date Feb. 25, 1998, now U.S. Pat. No.6,123,108 which is a Continuation-In-Part of Ser. No. 08/846,912 filedApr. 30, 1997 now U.S. Pat. No. 6,085,792.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a new energy attenuation apparatus for asystem conveying liquid under pressure and to a method of attenuatingenergy in such a system. The invention is particularly suitable forplacement in a system conveying liquid under pressure for theattenuation of pressure pulsations in the liquid, especially in thehydraulic system of the power steering unit of a vehicle. The inventionwould also be suitable for other hydraulic fluids.

2. Prior Art Statement

In hydraulic systems where the operating liquid is circulated by a pump,the pulsations of pressure that are generated by the pump aretransmitted through the conduits and result in noise and/or vibrationbeing produced by the hydraulic liquid. In the case of power steeringfluid in vehicles, such noise and/or vibration is caused, for example,when vehicles are being parked or unparked at idle or very low speeds ofmovement thereof, such as by barely moving into and out of a parkingspace or the like while the wheels of the vehicle are being turned bythe power steering mechanism thereof. In particular, substantial noiseand/or vibration (shudder) can be produced in such a situation when thepower steering fluid passes through the power steering mechanism fromthe fluid pump to the effective steering structure. Further backgroundin this area can be obtained from U.S. Pat. No. 3,323,305, Klees,whereby this U.S. Patent is being incorporated into this disclosure bythis reference thereto.

Devices are known for suppressing noise in exhaust gas mufflers. Forexample, U.S. Pat. No. 4,501,341, Jones, provides two side branchresonators, while U.S. Pat. No. 4,371,053, Jones, provides for anapertured tube in a gas muffler housing. Systems are also known forcontrolling the resonation of pressure waves in fuel injection systems.For example, U.S. Pat. No. 5,168,855, Stone, passes fluid through checkvalves that are provided with a flow restriction either directly thereinor in a bypass line. U.S. Pat. No. 5,509,391, DeGroot, provides a spoolvalve assembly for controlling flow between inlet and outlet ports.Henderson et al, U.S. Pat. No. 4,671,380, discloses a long and narrowtubular casing having a perforated tube extending therethrough. Finally,“Acoustics of Ducts and Mufflers”, by M. L. Munjal, provides a resonatorfor conveying gas in the form of an apertured tube disposed in a tubularcavity.

Applicants are not aware of any teaching of transferring flow of liquidunder pressure from one apertured conduit to another as a means ofsuppressing energy, from any apertured tube in a canister, nor from anapertured tube in a right cylindrical conduit.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide animproved apparatus and method for attenuating energy in a system thatconveys liquid under pressure.

This object is realized pursuant to the energy attenuation apparatus ofthe present invention by providing a tubular means having an inletopening for receiving liquid from the system, and an outlet opening forreturning the liquid to the system, wherein an inlet conduit extendsconcentrically into the tubular means, wherein an annular space isformed between the inlet conduit and the tubular means, and wherein in aportion of the inlet conduit disposed in the tubular means the inletconduit is provided with at least one aperture for introducing liquidtherefrom into the annular space.

Accordingly, it is an object of this invention to provide a novel energyattenuation apparatus having one or more of the novel features of thisinvention as set forth above or hereinafter shown or described.

Another object of this invention is to provide a new method ofattenuating energy in a system conveying liquid under pressure, themethod of this invention having one or more of the novel features ofthis invention as set forth above or hereinafter shown or described.

Other objects, uses and advantages of this invention are apparent from areading of the specification in conjunction with the accompanyingschematic drawings, which form a part thereof and wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a simplified automotive power steering system thatincorporates one exemplary embodiment of the energy attenuationapparatus of this invention;

FIG. 2 shows a power steering system utilizing the inventive energyattenuation apparatus;

FIG. 3 illustrates one exemplary embodiment of the inventive energyattenuation apparatus in a specific pressure line or return line of anautomotive power steering system;

FIG. 4 is a cross-sectional view of one exemplary embodiment of theenergy attenuation apparatus of this invention;

FIG. 5 is a view similar to that of FIG. 4 of a second exemplaryembodiment of the energy attenuation apparatus of this invention;

FIG. 6 is a view similar to that of FIG. 4 of a third exemplaryembodiment of an energy attenuation apparatus of this invention;

FIG. 7 is a view similar to that of FIG. 4 of a further exemplaryembodiment of an energy attenuation apparatus of this invention;

FIG. 8 is a view similar to that of FIG. 4 of yet another exemplaryembodiment of an energy attenuation apparatus of this invention;

FIG. 9 is a view similar to that of FIG. 4 of a further exemplaryembodiment of an energy attenuation apparatus of this invention;

FIG. 10 is a view similar to that of FIG. 4 of another exemplaryembodiment of an energy attenuation apparatus of this invention;

FIG. 11 is a cross-sectional view of another exemplary embodiment of theenergy attenuation apparatus of this invention;

FIG. 11a is a close up view of the end of the energy attenuationapparatus of FIG. 11;

FIG. 12 is a view similar to that of FIG. 11 of yet another exemplaryembodiment of an energy attenuation apparatus of this invention;

FIG. 13 is a view similar to that of FIG. 11 showing a further exemplaryembodiment of an energy attenuation apparatus of this invention;

FIG. 14 is a view similar to that of FIG. 11 showing a further exemplaryembodiment of an energy attenuation apparatus of this invention;

FIG. 15 is a view similar to that of FIG. 11 showing another exemplaryembodiment of an energy attenuation apparatus of this invention with arestrictor;

FIGS. 16-18 show portions of inlet and/or outlet conduits that areprovided with alternative configurations of apertures;

FIG. 19 illustrates a simplified automotive power steering system inwhich are disposed two energy attenuation apparatus of this invention;

FIGS. 20 and 21 show various embodiments of tuning cable arrangementsfor use in conjunction with the energy attenuation apparatus of thisinvention;

FIG. 22 illustrates one exemplary embodiment of the inventive energyattenuation apparatus of the present invention in conjunction with afurther attenuation apparatus in a specific pressure line or return lineof an automotive power steering system;

FIG. 23 is a partial block diagram showing one arrangement for use inconjunction with the present invention;

FIG. 24 is a graph showing the improvement in pressure attenuationachieved with the energy attenuation apparatus of this invention; and

FIG. 25 shows one exemplary embodiment of an inventive connector.

DESCRIPTION OF PREFERRED EMBODIMENTS

While the various features of this invention are hereinafter illustratedand described as providing an energy or sound attenuation apparatus foran automotive power steering system, it is to be understood that thevarious features of this invention can be utilized singly or in variouscombinations thereof to provide an energy attenuation apparatus forother systems that convey liquid under pressure.

Therefore, this invention is not to be limited to only the embodimentsillustrated in the drawings, because the drawings are merely utilized toillustrate one of the wide variety of uses of this invention.

Referring now to the drawings in detail, FIG. 1 illustrates a simplifiedautomotive power steering system. During operation, the power steeringpump 11 generates pressure ripples that are transmitted through tubing,such as steel tubing, to the pressure line 12, the power steering gear13, the return line 14, and the reservoir 15, and finally flow back tothe pump 11 itself by means of the supply line 16. It should be notedthat rather than being separated by a hose or similar conduit, thereservoir 15 and the pump 11 could actually be a single unit.

In order to greatly reduce such pressure ripples before they reach thegear 13 via the pressure line 12, and thereby eliminate or at leastgreatly reduce the power steering noise or vibration generated by thepower steering pump 11, the energy attenuation apparatus of thisinvention, which is generally indicated by the reference numeral 20, isillustrated as being disposed in the pressure line 12 between the pump11 and the gear 13. Various exemplary embodiments of the energyattenuation apparatus 20 and components and arrangements thereof areillustrated in FIGS. 2-23, and will be described in detail subsequently.

The energy attenuation apparatus 20 that is shown disposed in thepressure line 12 in FIG. 1 is shown in greater detail in FIG. 4. Inparticular, the energy attenuation apparatus 20 comprises a canister orhousing 21 that in the illustrated embodiment is a two-part housing madeup of the parts 22 and 23 that are interconnected by the ring 24. Inthis embodiment of the energy attenuation apparatus, a single chamber 25is formed in the housing 21. It is to be understood that the size andshape of the housing 21 can vary with the space available to accommodatesame as well as with the existing requirements. For example, athree-part housing could be used, including a central portion withidentical caps or end portions on each side thereof.

As shown by the arrow, liquid enters the housing 21, for example fromthe pressure side of the pump 11, by means of an inlet conduit 27, suchas a tube or pipe. As can be seen from FIG. 4, this inlet conduit 27extends well into the chamber 25 of the housing 21. In addition, theinlet conduit 27 is provided with a plurality of apertures or holes 28that allow the liquid to enter the chamber 25 from the conduit 27. Fromthe chamber 25, which is also known as a mixing area or a flow controlchamber, the liquid enters an outlet conduit 29 by means of a pluralityof apertures or holes 30 formed therein. The inlet and outlet conduits27 and 29 are sealingly disposed in the housing 21 in any convenientmanner, as indicated schematically at the locations 31 and 32respectively. As shown in FIG. 1 and the schematic view of FIG. 2 of aproposed power steering system utilizing the inventive energyattenuation apparatus, the outlet conduit 29 is connected to thepressure line 12 so that the liquid, in this case power steering fluid,can be conveyed to the gear 13.

Although the embodiment illustrated in FIG. 4 provides for a single,hollow chamber into which a straight inlet conduit extends and fromwhich a straight outlet conduit emerges, it has also been foundaccording to the teachings of this invention that other configurationsare possible. For example, reference is now made to FIGS. 5-15, whereinother housing and conduit configurations of this invention are shown andare generally indicated by the reference numerals 20A-20K, wherein partsthereof similar to the energy attenuation apparatus 20 of FIG. 4 areindicated by like reference numerals that where appropriate are followedby the reference letter A, B, C, D, E, F, G, H, I, J or K.

The embodiments illustrated in FIGS. 5 and 6 differ from that shown inFIG. 4 only in that the chamber 25 is partially filled with a flowcontrol or filler means. For example, the energy attenuation apparatus20A of FIG. 5 shows a housing 21 having a chamber 25 that is partiallyfilled with spherical filler means 34A. These filler means 34A can besolid or hollow beads or balls made of steel, rubber, plastic, or anyother suitable material, and help to increase the dissipation of energy.The filler means 34A, as well as the filler means to be discussedsubsequently, should be made of a non-corrosive material and should beable to withstand temperatures up to 300° F.

FIG. 6 illustrates an embodiment of an energy attenuation apparatus 20Bwherein the housing 21 has a chamber 25 that is partially filled withirregularly shaped flow control or filler means 34B. As was the casewith the filler means 34A of FIG. 5, the filler means 34B can be made ofany suitable material, again solid or hollow, and could even comprisegravel. A sponge or foam-like filler means could also be used as long asit is compatible with operating parameters.

The energy attenuation apparatus 20C illustrated in FIG. 7 shows ahousing 21 having chamber means that is not only partially filled withfiller means 34C, such as steel balls, but is also subdivided into aplurality of chambers by baffle plates, as will be discussed in greaterdetail subsequently.

FIGS. 8-10 illustrate how either one or both of the inlet and outletconduits can be bent, rather than having the straight configuration ofthe previous embodiments. For example, the outlet conduit 29D of theenergy attenuation apparatus 20D is bent at right angles prior toexiting the housing 21. Similarly, the inlet conduit 27E of the energyattenuation apparatus 20E of FIG. 9 is bent at right angles after havingentered the chamber 25 of the housing 21. It should be noted that thechambers 25 of the energy attenuation apparatus 20D and 20E could alsobe provided with a flow control or filler means.

In the energy attenuation apparatus 20F illustrated in FIG. 10, both theinlet conduit 27F and the outlet conduit 29F are bent at right angleswithin the housing 21 although they could also extend linearly as insome of the previously described embodiments. The attenuation apparatus20F also differs from the previously illustrated embodiments of FIGS.4-6, 8 and 9 in that the housing 21 does not contain a single chamber,but rather is divided into two chambers 35 and 36. This division of thehousing 21 into two chambers is effected by a further flow control meansin the form of a baffle 37, which in the illustrated embodiment isdisposed in the center of the housing 21. The baffle plate 37 isprovided with a plurality of holes 38 in order to allow liquid to flowfrom the chamber 35 to the chamber 36. Again, one or both of thechambers 35, 36 can be partially filled with filler means. In addition,multiple baffle plates could be provided, either adjacent one another orfurther subdividing the housing 21 into additional chambers, whereby theconduits 27F, 29F could even extend through some of the baffles. Forexample, FIG. 7 illustrates a housing 21 that is provided with threesuch baffles 45, each of which is provided with a plurality of holes 46in order to allow liquid to flow from the inlet conduit 27 to the outletconduit 29 through the various chambers 47-50 into which the housing 21is subdivided by the baffle plates 45. In the illustrated embodiment,the inlet and outlet conduits 27, 29 are illustrated as extending farinto the housing 21, thus extending through two or even all three of thebaffle plates 45. It will be understood that the inlet and outletconduits 27, 29 need not extend so far into the housing 21, and could,if desired, respectively extend through only a single one of the baffles45.

Although in the presently preferred embodiments the inlet conduit 27 isillustrated as being provided with six holes, while the outlet conduit29 is shown as being provided with eight holes 30, the number of holesas well as the dimensions and shapes thereof could vary, although it ispresently provided that the inlet conduit 27 have a lesser number ofholes or apertures than does the outlet conduit 29. The reversearrangement would be theoretically possible, whereby the importantfeature is that the number of holes of the inlet and outlet conduitsdiffer from one another. The number of holes, and the other parametersthereof, will vary as a function, for example, of the size of the pumpas well as of the operating conditions. In addition, the holes can beprovided on only one side of a given conduit, or on both sides thereof.In addition, although in the illustrated embodiments the holes areshowing as being aligned with one another in a longitudinal direction ofthe conduit, such holes could also be provided in a staggered orotherwise random configuration. It is expedient to have the holes of theinlet conduit angularly offset from those of the outlet conduit so thatthere is no direct flow between the conduits. If each conduit has onlyone row of holes, these rows could be offset by 180° relative to oneanother. If each conduit has two rows of holes, preferably disposed 90°apart, the rows of one of the conduits would be disposed so as to be 90°from the closest row of the other conduit.

Although the baffle 37 of the embodiment of the energy attenuationapparatus 20F shown in FIG. 10 is illustrated as extending in atransverse direction, a similar baffle plate could also be provided inthe embodiments of FIGS. 4-6, 8 and 9, wherein such baffle plate wouldthen be disposed in a longitudinal direction of the housing 21 betweenthe inlet and the outlet conduits.

It should also be noted that the inlet and outlet conduits need notnecessarily have the same length within the housing 21. In addition, thediameters thereof need not be the same. In addition, the diameter oreven the shape of the holes of the inlet and outlet conduits can differfrom one another.

Although the previously described embodiments provide for acanister-type housing, it has been found according to the teachings ofthis invention that a tubular housing, for example a hose or casing,could also be used. Furthermore, although the previously describedembodiments provide for separate inlet and outlet conduits 27, 29, ithas also been found according to the teachings of this invention thatthe inlet and outlet conduits could be a single conduit. For example,reference is now made to FIG. 11, wherein a single, continuous tube orconduit 52 of metal or polymeric material, such as Teflon, isillustrated. Although a straight conduit 52 has been shown, otherconfigurations are also possible. As with the previous embodiments, theembodiment of the energy attenuation apparatus 20G shown in FIG. 11 isalso provided with apertures in the peripheral surface of the conduit,although instead of the apertures 53, or in addition thereto, one of theends, namely a free end, of the tube 52 can be open, as will bediscussed in greater detail subsequently. In particular, in theembodiment illustrated in FIG.11 the apertures 53 are in the form ofholes, with two holes that are 180° apart being shown approximately inthe middle of the tube 52, although the holes 53 could also be disposedcloser to one end, for example a third of the way from the inlet end. Asdiscussed previously, various numbers and arrangements of such apertures53 are possible, and it would even be possible to provide only a singleaperture since only a single conduit is present. For example, four holescould be provided, with two holes being provided in the left handportion of the conduit 52 and two further holes being provided in theright hand portion of the conduit 52. In addition, four holes spaced 90°from one another could be disposed around the center of the tube orconduit 52. In addition, the apertures 53 can have any other desiredshape, such as an oval shape.

In contrast to a canister-type housing, in the embodiment illustrated inFIG. 11 the single conduit 52 is surrounded by a rubber hose 54, with anarrow annular space 55 of from {fraction (1/32)} to ⅜ of an inch orlonger being formed between the outer periphery of the conduit 52 andthe inner periphery of the hose 54. If the holes 53 are provided in theperipheral surface, the annular space 55 serves for receiving hydraulicfluid from the conduit 52 via such apertures 53 thereof; the liquid isagain returned to the conduit 52 via the apertures 53 and/or directly tothe tubing T of the liquid conveying means in which the energyattenuation apparatus of the present invention is disposed. The hose 54can also be made of polymeric material, or, as shown in the embodimentof the energy attenuation apparatus 201 of FIG. 13, can be made ofmetal. The tubular means 54, whether a hose or a casing, has aright-cylindrical cross-sectional configuration.

Although either end could be connected, in the embodiment illustrated inFIG. 11 the inlet end 71 of the conduit 52 (the left end in FIG. 11), isconnected in a fluid communicating manner to the tubing T of the liquidconveying means, for example via the unique connector to be describedsubsequently in conjunction with FIG. 25. In contrast, the right oroutlet end 70 of the conduit 52 is not directly connected to thecontinuation of the tubing T, although fluid communication is providedwith such tubing. In particular, the hose 54 is squeezed or crimpedbetween the outer surface of the tubing T and the inner surface of acoupling 72, for example a coupling made of metal such as steel oraluminum, or of a suitable hard polymeric material. The outlet end 70 ofthe conduit 52 extends within the region of the coupling 72, but is notconnected to either the hose 54 or to the tubing T, in other words, theoutlet end 70 is a free end. This free end 70 of the conduit 52 canextend slightly into the region of the coupling 72, can extend, forexample, half way into the coupling 72, or could even extend into thetubing T itself, for example from one inch up to twelve inches or more.

Although in the embodiment illustrated in FIG. 11 apertures 53 are shownin the peripheral surface of the conduit 52, pursuant to one specificembodiment of the energy attenuation device of the present invention nosuch holes or apertures 53 are provided. Instead, the free end 70 of theconduit 52 is open, with the liquid from the conduit 52 thus exiting thefree end 70. If holes 53 are provided, either as an alternative or inaddition to the open free end 70, liquid exiting the conduit 52 via theholes 53 thereof into the annular space 55 can again exit this space atthe free end 70 for reentry into the tube T at that location.

In the embodiment of the energy attenuation apparatus 20H illustrated inFIG. 12, a single conduit 52H is again shown. However, in thisembodiment the conduit 52H does not extend all the way from the inletend to the outlet end of the hose 54H, but stops short of the outletend; the conduit 52H can end 0.25 to 9 inches or more from the outletend of the hose 54H, and in one exemplary embodiment of the presentinvention, for a conduit length of 11 inches, ends 1.5 inches from theoutlet end of the hose 54H.

A combination of the concepts illustrated in the apparatus of FIGS. 4-10on the one hand and FIG. 11 on the other hand is illustrated by way ofexample in the energy attenuation apparatus 20J of FIG. 14. In thisembodiment, again two separate inlet and outlet conduits 27J, 29J areprovided. However, instead of being disposed next to one another, theseinlet and outlet conduits are aligned with one another and are separatedfrom one another by a slight gap 56, for example a gap of approximately{fraction (1/32)} (presently preferred) to ⅛ of an inch, or even up toone inch or more. Again, the inlet conduit 27J is provided withapertures 28, while the outlet conduit 29J is provided with apertures30.

The embodiments of the energy attenuation apparatus of FIGS. 11-14 canalso be provided with any of the other features of the previouslydiscussed embodiments, such as the flow control means or filler means34, as well as one or more flow control means in the form of baffleplates. In addition, a restrictor means could be provided in one or moreof the conduit means 27, 29 or 52. For example, the energy attenuationapparatus 20K of FIG. 15 shows such a restrictor 57 disposed in thecentral portion of the conduit 52. Such a restrictor 57 could beprovided at either end of the conduit 52, or at both ends, and couldalso be provided in one or both of the inlet and outlet conduits 27, 29of some of the previously described embodiments. It is to be understoodthat the passage 58 through the restrictor 57 has an inner diameter thatis smaller than the inner diameter of the tube or conduit in which it isdisposed. For example, the passage 58 of the restrictor 57 could have adiameter of from 0.36 to 0.10 of an inch.

Although the conduits 52 could be connected at both ends, pursuant toanother inventive embodiment, in a manner similar to that described inconjunction with FIG. 11, one end of each of the conduits 52 is a freeend. In particular, in the embodiment illustrated in FIG. 15, eachconduit 52 is connected at one end to the restrictor 57, while the otherend is a free end in the same manner as described in conjunction withthe conduit 52 of the embodiment of FIG. 11. If the free ends are open,neither conduit need be provided with holes on its peripheral surface.Alternatively, or in addition to the free ends being open, at least oneof the conduits can be provided with at least one hole in its peripheralsurface.

FIG. 25 illustrates a novel connector 75 for interconnecting the conduit52 in a fluid communicating manner with the tubing T. The connector 75can be made of metal, such as stainless steel or aluminum, or of asuitable plastic or polymeric material. The connector includes a hollowcylindrical portion 76 that is adapted to be inserted into the tubing T,where the tubing T can be crimped to the cylindrical portion 76 toprovide a secure connection between the tubing T and the connector 75.At the opposite end, the connector is provided with a hollow barbed orridged portion 77 having appropriate barbs or ridges 78 thereon. Theconduit 52 is held on the portion 77 by means of such barbs or ridges78. For this purpose, the inner diameter of the conduit 52 is preferablyslightly less than the outer diameter of the non-ridged part of theportion 77 of the connector 75. The end 80 of the ridged portion 77 canbe tapered inwardly toward the end to facilitate insertion of theportion 77 into the conduit 52. A collar 81 is provided on the outerperiphery of the hollow connector 75 between the cylindrical portion 76and the ridged portion 77 thereof. This collar 81 provides an abutmentmeans for the tubing T on the one hand and for the conduit 52 on theother hand.

Referring now back to FIG. 11, and in particular to the left sidethereof, the connector 75 can provide for the interconnection in a fluidcommunicating manner of the conduit 52 to the tubing or liquid conveyingmeans T. In particular, the hose 54 can again be crimped between theouter surface of the tubing T and the inner surface of a furthercoupling 82. The cylindrical portion 76 of the connector 75 is securedin the tubing T, with a connector 75 being inserted, for example, up tothe collar 81 thereof, with the ridged portion 77 of the connectorextending out of the tubing T. The tubing T can either end within thecoupling 82, or can even extend slightly into the chamber formed by thehose 54, in which case the ridged portion 77 of the connector 75 extendsinto this chamber. The conduit 52 is then secured to the ridged portion77 via the barbs or ridges 78 thereof.

In a similar manner, with respect to FIG. 15 the connection of the twoconduits 52 to the restrictor 57 can be effected by respectiveconnectors having a configuration similar to that described inconnection with the connector 75.

Although the inlet and outlet conduits 27, 29 illustrated in thepreviously described embodiments have primarily been provided withspherical holes 28, 30, it is to be understood that any other desiredshape could also be used. By way of example only, FIGS. 16-18 show someother shapes for the holes in the inlet and outlet conduits. Forexample, the inlet and/or outlet conduit 40 illustrated in FIG. 16 isprovided with oval apertures 41. The inlet and/or outlet conduit 42 ofFIG. 17 is provided with triangular apertures 43. And the inlet and/oroutlet conduit 44 of FIG. 18 is provided with rectangular apertures 45.

It should also be noted that although in the illustrated embodiments theinlet and outlet conduits are shown as having closed ends within thechamber or chambers of the housing 21 or hose 54, the ends of the inletand/or outlet conduits can also be opened, or could also be providedwith holes, and the apertures or holes 53 on the periphery of theconduits could be omitted.

It should furthermore be noted that although the inventive energyattenuation apparatus 20 has been illustrated in FIG. 1 as beingdisposed between the pump 11 and the gear 13, it is believed that suchan attenuation apparatus could alternatively be disposed between thegear 13 and the reservoir 15 in the return line 14 in order to reducevibration caused by the power steering gear 13. Furthermore, twoattenuation apparatus could be provided. For example, FIG. 19 shows asystem having two energy attenuation apparatus 20, one in the pressureline 12 to a control valve 17 (similar to the gear 13 of FIG. 1), andanother in the return line 14. FIG. 3 illustrates an exemplaryembodiment of an actual pressure or return line (bent to accommodatespace requirements) in which is disposed an inventive energy attenuationapparatus 20, which in this embodiment is provided with an optionalventing means 43.

The inventive energy attenuation apparatus which is a ¼ wave device, canalso be used in conjunction with a variety of other sound and vibrationattenuation apparatus, which are then also disposed in the pressure line12 and/or the return line 14. For example a ¼ wave cable tuning assemblycan be provided, for example by disposing a steel cable in a separatehose section. Examples of such tuning cable arrangements in hosesections are shown in FIGS. 20 and 21, wherein FIG. 20 shows a singletuning cable 59 disposed in the hose section or conduit means 60,whereas FIG. 21 shows two separate tuning cables 59 disposed in a hosesection or conduit means 60. If the tuning cable or cables are made ofpolymeric material, such as Teflon, they can also be provided withapertures in the peripheral surface thereof. An example of a knowntuning cable is disclosed in the aforementioned patent to Klees, U.S.Pat. No. 3,323,305, which patent has been incorporated into thisdisclosure. The tuning cable arrangements in the conduit means 60 can bedisposed in series with the inventive energy attenuation apparatus, asillustrated in FIG. 22, or can be disposed in parallel therewith. Othersound and vibration attenuation apparatus are also known. For example,reference is made to U.S. Pat. Nos. 4,611,633 (Buchholz et al),5,172,729 (Vantelini) and 5,201,343 (Zimmermann et al) whereby such U.S.Patents are also being incorporated into this disclosure by thisreference thereto. Furthermore a springtype energy attenuation device asdisclosed in applicants' copending U.S. patent application Ser. No.08/853,770 could also be provided, whereby the disclosure of suchapplication is also incorporated into this disclosure by this referencethereto. One or more of such other attenuation apparatus could also beused in conjunction with the energy attenuation apparatus 20-20K of thepresent invention. For example, FIG. 23 shows an arrangement where thetubing T is split into branches 62, each of which leads to an energyattenuation apparatus that is schematically indicated by one of theboxes 63 or 64. This parallel arrangement can either be disposed inseries with one of the inventive attenuation apparatus 20-20K, or one ofthe boxes 63, 64 can contain an inventive energy attenuation apparatuswhile the other box contains a known attenuation device. Furthermore,both boxes 63 and 64 can contain the same or different ones of theinventive energy attenuation apparatus. It should also be noted that twoor more of the inventive energy attenuation apparatus could be disposedin series and/or in parallel with one another. For example, in theexemplary embodiment illustrated in FIG. 3, the portion shown as a hosesection can be one or more of the embodiments illustrated in FIGS.11-15. In addition although FIG. 3 shows a canister type energyattenuation apparatus 20, this could be replaced by another one of theembodiments of FIGS. 11-15, or any one of the aforementioned alternativeattenuation apparatus, including the apparatus of applicants' copendingU.S. patent application Ser. No. 09/006,068, whereby the disclosure ofsuch application is also incorporated into this disclosure by thisreference thereto.

In one exemplary embodiment of the energy attenuation apparatus 20 ofthis invention as illustrated in FIG. 4, the housing 21 and the inletand outlet conduits 27, 29 were made of stainless steel. The housing 21had an approximately cylindrical shape, and in a small embodimentthereof had a length of approximately 85 mm, a diameter of approximately50.1 mm, and a thickness of approximately 1 mm. The stainless steelinlet and outlet conduits 27, 29 had an inner diameter of approximately9.5 mm (⅜ of an inch) and a thickness of approximately 1 mm. Thediameter of the holes in the inlet and outlet conduits 27, 29 wasapproximately 3.89 mm.

In order to provide sufficient volume or space between the outerperiphery of the inner conduit or conduits and the interior of thehousing or canister, the ratio of the diameter of the housing means tothe diameter of the conduit should be at least 2:1, and could be as muchas 10.7:1 or even greater. The housing means 21 can be a substantiallycylindrical canister, or could be egg shaped or even spherical. A largevolume can also be achieved for the narrow hose or casing embodiments byproviding for a very long hose or casing, for example one having alength of several feet, such as even seven feet or longer if sufficientspace is available.

In exemplary embodiments of the energy attenuation apparatus 20G of FIG.11, the hose 54 had a length of approximately 5 to 40 inches or greaterand a diameter of ⅜ to ⅝ of an inch or greater. The diameter of theconduit 52 was ⅜ of an inch or less.

As indicated previously, the pressure pulses resulting from therevolutions of the pump create harmonics and noise. This phenomenon,along with the significant improvement provided by the inventive energyattenuation apparatus, is shown in FIG. 24, wherein pressure is plottedagainst the harmonics order of a given pump, with this pump generatingten pulses per revolution thereof. These 10 pulses are considered as the10th order with the following harmonics being 20th, 30th, etc. Thisgraph, which was plotted for the system of FIG. 1, namely the embodimentof the energy attenuation apparatus 20 of FIG. 4, was effected at asystem pressure of 900 psi and a pump speed of 1200 RPM. The pressure atthe outlet end of the pump is shown in the upper portion of the graph,whereas the pressure in the pressure line downstream of the energyattenuation apparatus is shown in the lower portion of the graph. Thesignificant improvement accomplished with the inventive energyattenuation apparatus can be clearly seen from this graph. For example,for the tenth order of the pump, a reduction of about 56% is achieved,while for the 20th order, a reduction of about 62% is achieved.Subsequent to the 20th order, the pressure pulses are nearly entirelyeliminated.

In view of the foregoing, it can be seen that this invention not onlyprovides a new energy attenuation apparatus, but also this inventionprovides a new method for attenuating sound or energy in a liquidconveying system.

While the forms and methods of this invention now preferred have beenillustrated and described as required by the Patent Statute, it is to beunderstood that other forms and method steps can be utilized and stillfall within the scope of the appended claims, whereby it is believedthat each claim sets forth a novel, useful and unobvious inventionwithin the pervue of the Patent Statute.

What is claimed is:
 1. An energy attenuation apparatus for a systemconveying a liquid under pressure, wherein said apparatus is disposed ina liquid conveying means of said system, said apparatus comprising: atubular means that forms a single chamber having either an inlet openingor an outlet opening that is in fluid communication with said liquidconveying means for receiving liquid from or returning liquid to saidsystem; and a conduit coupled at one end thereof in a fluidcommunicating manner with said liquid conveying means for receiving saidliquid from or returning said liquid to said system, wherein saidconduit is disposed essentially concentrically in said single chamber ofsaid tubular means, wherein an annular space is formed between saidconduit and said tubular means, wherein said conduit is provided with atleast one aperture for allowing said liquid to exit said conduit, andwherein a free end of said conduit extends to the vicinity of said inletor outlet opening of said single chamber of said tubular means but isnot connected to said liquid conveying means at that location.
 2. Anenergy attenuation apparatus according to claim 1, wherein said tubularmeans is connected to said liquid conveying means via respectivecoupling means.
 3. An energy attenuation apparatus according to claim 2,wherein said free end of said conduit extends within the region of oneof said coupling means.
 4. An energy attenuation apparatus according toclaim 3, wherein said free end of said conduit extends to within halfthe length of said coupling means.
 5. An energy attenuation apparatusaccording to claim 3, wherein said free end of said conduit also extendsinto said liquid conveying means.
 6. An energy attenuation apparatusaccording to claim 3, wherein said free end of said conduit is open orclosed.
 7. An energy attenuation apparatus according to claim 6, whereinat least one hole is provided in a peripheral surface of said conduit.8. An energy attenuation apparatus according to claim 3, wherein saidfree end of said conduit is open, and no holes are provided in aperipheral surface of said conduit.
 9. An energy attenuation apparatusaccording to claim 3, wherein a connector is coupled to said liquidconveying means, and said one end of said conduit is coupled to saidconnector.
 10. A system incorporating said energy attenuation apparatusof claim 1 and further including at least one further energy attenuationapparatus of any desired type is disposed in series with or parallel tosaid first mentioned energy attenuation apparatus.
 11. An energyattenuation apparatus for a system conveying a liquid under pressure,wherein said apparatus is disposed in a liquid conveying means of saidsystem, said system comprising: a tubular means that forms a chamberhaving an inlet opening that is in fluid communication with said liquidconveying means for receiving said liquid from said system, and havingan outlet opening that is in fluid communication with said liquidconveying means for returning said liquid to said system; a restrictordisposed in said chamber and dividing same into an inlet chamber and anoutlet chamber; a first conduit disposed essentially concentrically insaid inlet chamber and connected in a fluid communicating manner to saidrestrictor, wherein an annular space is formed between said conduit andsaid tubular means, wherein a free end of said first conduit extends tothe vicinity of said inlet opening of said chamber of said tubular meansbut is not connected to said liquid conveying means, and wherein saidfirst conduit is provided with at least one aperture for receiving saidliquid; and a second conduit disposed essentially concentrically in saidoutlet chamber and connected in a fluid communicating manner to saidrestrictor, wherein an annular space is formed between said secondconduit and said tubular means, wherein a free end of said secondconduit extends to the vicinity of said outlet opening of said chamberof said tubular means but is not connected to said liquid conveyingmeans, and wherein said second conduit is provided with at least oneaperture for returning said liquid.
 12. An energy attenuation apparatusaccording to claim 11, wherein said tubular means is connected to saidliquid conveying means via respective coupling means.
 13. An energyattenuation apparatus according to claim 12, wherein said free ends ofsaid first and second conduits respectively extend within the region ofone of said coupling means.
 14. An energy attenuation apparatusaccording to claim 13, wherein said free ends of said first and secondconduits extend to within half the length of said coupling means.
 15. Anenergy attenuation apparatus according to claim 13, wherein the free endof at least one of said first and second conduits also extends into saidliquid conveying means.
 16. An energy attenuation apparatus according toclaim 13, wherein said free ends of said first and second conduits areopen or closed.
 17. An energy attenuation apparatus according to claim16, herein at least one hole is provided in a peripheral surface of atleast one of said first and second conduits.
 18. An energy attenuationapparatus according to claim 13, wherein said free ends of said firstand second conduits are open, and at least one of said conduits has noholes in a peripheral surface thereof.
 19. A connector forinterconnecting a conduit in a fluid communicating manner with a liquidconveying means, said connector comprising: a first hollow cylindricalportion for insertion into and for a crimped connection to said liquidconveying means; and a second hollow barbed or ridged portion forinsertion into and connection to said conduit.
 20. A connector accordingto claim 19, wherein a collar is provided between said first and secondportions to provide respective abutments for said liquid conveying meansand said conduit respectively.
 21. A connector according to claim 20,wherein an end of said barbed or ridged portion opposite said collar istapered inwardly in a direction away from said collar.